THE GEORIFT 2013 WIDE-ANGLE SEISMIC PROFILE, PRELIMINARY RESULTS

The GEORIFT 2013 deep seismic sounding (DSS) experiment was carried in August 2013 on territory of Belarus and Ukraine in wide international co-operation: Belarusian, Ukrainian, Danish, Finnish and. Polish. The aim of the work is to study the deep-seated structure and geodynamic development of lithosphere across East European Craton (EEC). The GEORIFT-13 profile runs across structures of different order and age, along Pripyat-Dnieper-Donetsk depression with a number of faults. The total profile length was 675 km: 315 km on the Belarusian territory and 360 km in Ukraine. The field acquisition included 14 shotpoints (charge 600-1000 kg of TNT) every ~50 km (7 shotpoints in Belarus and 7 in Ukraine), and 309 recording stations every ~2.2 km. The data quality of the experiment was good, with visible first arrivals as far as up to 670 km (minimally up to 300 km). We present preliminary model of the structure to the depth of 60 km. Raytracing forward modelling (SEIS83 package) were used for the modelling of the seismic data. Large variations in the internal structure of the crust and the Moho topography were detected. The depth of the Moho varies from ~47 km in the northwestern part of the model, to 40 km in central part, and to ~38 km in the southeastern part of the profile. The sub-Moho velocities are ~8.25 km/s. Second, near-horizontal mantle discontinuity was found in the north-western part of the profile at the depth of 50-47 km. It dips to the depth of ca. 60 km at distances of 320-370 km, similarly as on crossed EB‟97 profile (Thybo et al., 2003).